Process for refining unsaturated hydrocarbon material with an alkali or alkaline earth metal



Patented 1946 'QFFHCQE HYDROGARBON MATERIAL WITH AN AL- KALI R EARTH METAL Frank J. Soday, Swarthmore, Pa, assignor to The United Gas Improvement vania poration of Pennsyl Company, a cor- No Drawing. Application 24, 1942,

' Serial No. 470,078

This invention relates to the purification of unsaturated hydrocarbons.

More particularly, this invention is concerned with the removal of certain impurities from unsaturated hydrocarbons, or mixtures thereof.

An object of. the present invention is the removal of certain impurities from unsaturated hy-- drocarbons by the application of at least one finely divided metal of groups In and 11a of the periodic system, or active alloys thereof. Another object of the invention is the refining of oleilnes,-

or fractions or mixtures containing at least one oleflne, under conditions designed to. reduce the losses incurred in such operations. Other objects and advantages of the invention will be apparent to those skilled in the art upon an inspection 0 the specification and claims.

Unsaturated hydrocarbons and unsaturated hydrocarbon fractions,- particularly those obtained by the pyrolysis of petroleum or of petroleum hydrocarbons, frequently contain substantial proportions of impurities which interfere with their use in most, if not all, industrial applicat ons.

Thus, unsaturated hydrocarbons obtained by the pyrolysis of petroleum may contain impurities such as acetylenes, aldehydes, peroxides, phenolic compounds, other oxygen-containing compounds,

sulfur-containing compounds, such as disulfldes and mercaptans, nitrogen-containing compounds, and the like. These compounds may be present in proportions ranging from traces to several percent depending, among other things, upon the boiling range of the particular fraction or mixture in question, the characteristics of the petroleum or petroleum fraction from which it was obtained, and the cracking temperature, as well as other pyrolysis conditions, employed.

as... (crate-.611)

. may be refined by the application in finely divided formof at least one metal or group Ia and group no of the periodic table, as well as certain active alloys thereof. Particularly desirable results are obtained by the use of finely divided alkali and alkaline earth metals.

Examples of such metals are lithium, sodium,

potassium, rubidium, caesium, barium, strontium and calcium- Due to the availability and low cost of sodium and potassium, however, these metals are preferred for the use set forth herein.

Alloys of these metals, such as NaPb1o,NaI-lg4, NaCas, NaZmz, Ella, and theiike, also maybe employed-for the removal of undesired impurities fromunsaturated hydrocarbons. Ingeneral, the alloys of the respective metals react with the impurities present in such materials at a slower rate 4 than the corresponding metals.

The removal of one or more impurities from unsaturated hydrocarbons or unsaturated hydrocarbon fractions is complicated generally by the ease with which such materials may be polymerized. The application of the refln'ing techniques customarilyemployed for the removal of impurities from hydrocarbons or hydrocarbon fractions which are preponderantly saturated and/or aro'- matic in character, such as gasoline, kerosene, light petroleum distillates, coal tar fractions, and the like, to unsaturated hydrocarbons or unsaturated hydrocarbon fractions frequently leads to the conversion of a substantial proportion, or all. of such materials to inferior types of polymers.

As a result of extensive experimentation, I have discovered that unsaturated hydrocarbons and Mind that a solution of sodium, or a suspension or emulsion of very finely divided sodium, or a solution, suspension, or emulsion of one or more sodium alloys or active compounds, is a particularly desirable agent for the removal of certain undesirable impurities iromunsaturated hydrocarbons. Excellent'results are obtained by the .use of a" suspension of very finely divided sodium.

The alkali metals, particularly sodium and potassium. are very active catalysts for the polymerization of unsaturatedhydrocarbons, Thus, practically all of the early work on the preparation of synthetic rubber from isoprene, bothin this country and abroad, was based on the use of sodium and/or potassium as the catalyst. Con-Y sequently, the use of such an active catalyst, particularly in finely divided (and hence most active) form, for the refining of unsaturated hydrocarbons would be expected to result in theconversion of the greater portion, if not all, of the unsaturated hydrocarbon to polymers. v.

It should be emphasized that the success of the refining operations is dependent upon rigid ad- Y herence to certain operating conditions such as temperature, reaction time, concentration, and so forth, which will detail.

Unsaturated scribed herein include hydrocarbons containing at least one double bond such as oleflnes, for exunsaturated hydrocarbon fractions and mixtures fining of olefines, such as aliphatic-defines.

be discussed in considerable hydrocarbons which may be refined by methods to be more particularly deis the by-product obtained upon the concentraamazes tion of diolefines, such as butadiene. Thus. the

olefine fraction obtained upon the concentration of a butadiene fraction usually contains substantial, and generally contains predomina ing. Pro- 7 portions of isob'utylene. Such fractions may be refined readily by the process disclosed herein.

A preferred embodiment of this-invention is the refining of isobutylene or of unsaturated hydrocarbon fractions in which isobutylene is the.

prepondering unsaturated hydrocarbon present.

Buchfractions also may contain minor.propor-- tions of one or more diolefines.

While the refining operations may be rrigged f added e on 1 out m the absence any polym be treated. I find that hydrocarbons and hyem one or more lyinhibitors I prefer to p y p0 drocarbon fractions are particularly desirable.

merization inhibitors in order to reduce the loss of the unsaturated hydrocarbons in the form of be refined then is passed purities present at the temperature employed.

Other methods of contacting -the material to 'be treated and the refining agent also may be employed if desired. Thus, the unsaturated-hydrocarbonv may be passed through a horizontal polymers, as well as to increase the limits of the permissible reaction variables.

Excellent results may be obtained when one or more inhibitors selected from a list comprising (1). secondary aryl amines such as phenyl betanaphthylamine, diphenyl-p-phenylene dlamine,

isopropoxydiphenyl amine, aldol-alpha-naphthylamine (and polymers thereof), symm. dibeta-naphthyl p-phenylene diamine, trimethyl dihydroquinoline (and polymers thereof),'and the ditolylamines;' (2) phenolic compounds, such as p-tertiary but? catechol and alkylated polydroxy phenols; a d (3) reaction products of a ketone, such" as I n such as formaldehyde and acetaldehyde. with an than 5% inhibitor and even 2% inhibitor in certain cases, particularly when one or more of the inhibitors listed in the preceding paragraph are employed.

While the refining operations may be carried cetone, and/or an aldehyde,

treating unit, such as a pipe or bank of pipes, containing a suspension of the desired'refinins agent, or otherwise.

The suspending liquid employed for the refining agent may be of any desired type, provided that it does not reactwith the reagent or the material to be treated to any substantial extent, and provided that it does not introduce any additional impurities into the material to materials for use as suspending mediums for refining agents of the type described herein. Excellent results have been obtained by the use of aromatic hydrocarbons and aromatic hydrocarbon fractions for this purpose.

It is to be understood, of course, that the material to be treated may dissolve to some extent in the suspending medium, consequently the suspending medium actually employed in the opamine, such as aniline, are used in the refining eration of the process usually comprises a mixture of the material to be treated and the suspending medium initially introduced into the system.

The unsaturated hydrocarbon being treated also may serve as a suspending medium for the refining agent without the addition of any other material, if desired. Thus, the unsaturated hydrocarbon or unsaturated hydrocarbon fraction may be introduced into the desired tower or vessel, together with the finely divided. refining agent, after which the material to be treatedis passed into the suspension of the refining agent I in the unsaturated hydrocarbon at the desired out in a satisfactory manner in a batchwise manner, I prefer to conduct such operations in a continuous or semi-continuous system in order to reduce the proportion of unsaturated hydrocarbon lost in the form of polymers, as well as to secure greater economy in the use of the reagent.

'The preferred refining method disclosed herein differs fundamentally from all methods described heretofore for'the refining of unsaturated hydrocarbons in that the material in question is treated with a metal of group IA or group'IIA,

or an active alloy of such metals, in finely dias thequantity and type of impurities present, the extent to which such impurities are to be re- I drocarbons due toside reactions or to polymerization is very markedly reduced, or almost completely'eliminated.

Although the process may be carried outin any-desiredmanner I prefer to conduct it in a vertical vessel or tower in which a certain height of a liquid suspension or solution of the active refining agent is maintained. The material to temperature, the charging rate and more par-.

ticularly the operating pressure being adjusted to maintain the treating agent at the desired level in the vessel.

It is to be understood, of course, that the portion of the material to be treated which has been dissolved in the suspending medium or which be treated. The major portion of the material to be treated, of course, bubbles up through the suspending medium without dissolving therein.

' The thickness of the layer of reagent through which the material to be treated is preferably passed depends upon a number of factors, such moved, the type and degree of dispersion of the treating agent employed, the reaction temperature, the concentration of the treating agent in the suspending medium. and the like. In general,'however, I prefer to employ a layer of reagent at least one foot thick and, more preferably, at least two feet thick. Excellent. results upward column of liquid at a rate suilicient to insure the a removal of the desired quantity and type ofimof refining obtained. In thecase'of sodium, I-

prefer to emp oy a subdivided mass in which at least the maJority of the particles present .have a diameter of not more than 0.05; and, more preferably, not more than 0.03"; Excellent results are obtained when at least the majority of the particles present have a diameter of not more than 0.02". This subdivision may be carried out in any desired manner. Thus. in the case of sodium, a solution of this material in liquid ammonia may be introduced into an inert liquid, such as xylene, at room temperature or at elevated temperatures. The almost instantaneous volatilization of the ammonia present results in the dispersion of the sodium present in the xylene in an extremely finely divided state. Another method comprises spraying molten sodium into an inert liquid such as xylene or solvent naphtha. By suitable vari ations in the type and degree of fineness or in the dispersing ability of the spray nomle employed,

or both, sodium of almost any desired degree of fineness may be obtained at will. Anothersatisfactory method comprises melting the sodium under the surface of a suitable liquid, such as xylene, followed by violent agitation, such as with a turbo-mixer, and cooling with agitation. Other methods which may be used include extrusion through fine orifices, and the generation of an are between sodium electrodes in an inert liquid Although almost any desired concentration of treating agent in the suspending medium may be employed, depending upon the type and concenat subatmo'spheric pressures, thereby reducing the concentration of the unsaturated hydrocars bon present in the refining system at a given reaction temperature. This serves to reduce the quantity of unsaturated hydrocarbon converted to polymers in the process, consequently, it is a preferred embodiment of this invention.

The temperature at which the process is conducted also has a very considerable bearing upon the degree to which the unsaturated hydrocarbon is refined and the, losses incurred due to polymerization. Although the optimum reaction temperature to be employed is dependent large- 1y upon other factors, such as the concentration of both the unsaturated hydrocarbon and the refining agent in the reaction zone, I generally prefer to conduct the refining operations at temperatures below 100 C. and. more particularly, below 80 C. ,Excellent results are obtained by con-- ducting the refining operations at temperatures below 70 C.

The rate at which the material to be refined is passed through the reagent has a very considerable efiect upon the degree to which the impurities present are removed, although this is dependent to some extent upon other variables such as the concentration of refining agent in the suspending medium and the temperature, at

. which the refining operations are being conduct- I generally prefer not to exceed a throughput of tration of the unsaturated hydrocarbon in the less than 30% and more particularly less than 20% by weight of the treating agent. Excellent results are obtained when less than 15 by weight of the treating agent is suspended in the suspending medium.

It is to be understood, of c'ourse, that the term suspending medium refers to the actual-suspend ing agent employed during the treating operation, and includes any of the material being treated which may dissolve in such agent.-

The concentration of the unsaturated hydrocarbon to be treated also has a considerable infiuence upon the method of operating the process. I generally prefer to employ such proportion of suspending medium that the actual concentration of the unsaturated hydrocarbon in the reaction zone is less than 80% and, more preferably, less than 70%. Excellent results are obtained when the actual concentration of unsaturated hydrocarbon in the reaction zone is less than 60%.

The process may be carried out at any desired pressure, such as atmospheric, subatmospheric,-

material to be treated on an hourly basis of more than four times the weight of'suspendirm medium employed and more preferably, not more than twice the weight of the suspending medium. Excellent results are obtained when not more than equal quantities of material to be treated, upon'an hourly basis, are passed through the suspending medium.

It will be recognized that the contact time between the material to be treated and the reagent is determined both by the thickness of'the layer of reagent employed and by the rate at which the material to be treated is passed through the re-,

eous material to be refined is desired. This may be accomplished by introducing the material to be treated into the reagent by means of suitable orifices, jets, nozzles, or other subdividing means. Porous objects or materials also may be employed for this purpose, such as porous ceramic or glass diffusing blocks or units.,

As the refining agent may show some tendency to settle out in the bottom of the treating vessel or unit, the jets or nozzles by means of which the material to be treated is introduced into the unit may be so arranged as to prevent any undue set-- tling of this material. In vertical vessels, this may be accomplished by locating these units in such a way as to impinge the inlet stream or streams upon the bottom of the treating vessel. The inlet Jets also may be arranged tangentially to'impart a swirling or circular motion to the treating reagent, if desired. Another method comprises locating the inlet jet or jets directly 7 in the bottom of the reactor, or tangentially in the sides of the reactor, or both, to prevent any settling in the bottom of the reacting vessel and form corresponding metallic derivatives.

7 to impart any desired circular or other motion to the treating medium.

Any desired combination of these methods also may be employed, such as the use of a jet or jets directly impinging upon the bottom of the reac-' tor in conjunction with the'use of a tangential jet or jets to prevent the active agent from settling out and depositing on the walls of the reactor and to maintain the reaction medium in any desiredstate of agitation.

The reaction medium also may be maintained in the desired degree of agitation by the use of suitable stirring or mixing devices, or by the use of circulating pumps, or by a combination of these methods, or otherwise. One or more of these methods also may be used in conjunction with one or more of the methods discussed previously to maintain the system in the desired degree of dispersion.

It should be pointed out, howeventhat the use of such agitation methods is not required in most cases. Thus, excellent results have been secured by conducting the refining operations in a tower, the material to be treated being introduced into the bottom of the tower by means of a small orifice. The passage of the fraction being treated in the gaseous state upward through the column usually is sufilcient to maintain the system in the desired degree of agitation.

. The refining agent, particularly when finely divided sodium is employed for this purpose, usually acts both as a reactant and as a polymerizing agent for the removal of undesired impurities. Thus, in the case of unsaturated hydrocarbon fractions containing acetylenes, aldehydes, and other impurities, the sodium usually will react with at least a portion of the acetylenes present to form sodium acetylides, and may react with certain of the oxygenated derivatives to At least a portion of the acetylenic hydrocarbons present also are polymerized to form polymers,

or copolymers with other unsaturated hydrocar-' bons present, which polymers frequently are insoluble in nature. Certain of the oxygenated derivatives, such as aldehydes, also may be polymerized to form polymers which may be insoluble in type.

As a result, the refining of unsaturated hydrocarbons with a suspension of finely divided sodium usually is characterized by the gradual accumulation-of insoluble polymers in the refining medium, This may be removed in any desired manner, such as by filtration, which may be carried out continuously during the refining operation, or may be carried out in a batchwise manner after the termination of the refining step.

As the removal of the insoluble polymers also is attended by some loss or refining agent, even when the latter is in a very fine state of subdivision, it is advisable in many cases to continue the refining operations until the refining agent has been largely or. completely exhausted before.

filtering. I

The solid or semi-solid filtered products may be treated to -recover any desired materials or they may be disposed of in any suitable manner.

, Thusfany unchanged refining agent, such as may be recovered by melting'and coalescing? operations, or by amalgamation with ni'er'curyjor otherwise. Certain of the reaction prfdtii'icts, such as sodium acetylides, may be decomposed 'with water to regenerate the corresponding' 'acids or they may be reacted with a 8 carbon dioxide to form unsaturated acids, oi otherwise.

A convenient method for the disposal of the insoluble polymers comprises treatment with carbon dioxide, suitably in the presence of traces of moisture, followed by filtration.

As the cost of the treating process is largely a function of the quantity of the reactive agent employed in the refining operations, the efficient utilization of such agent is of considerable importance. A desirable method for insuring optimum utilization of the treating agent is to carry out the operations in a continuous countercurrent manner, the reagent moving through the system in a manner countercurrent to that of the material to be treated.

This may be illustrated by means of a consideration of a simple continuous countercurrent system comprising two treating towers or 'vessels. The material to be treated is passed into the first tower, which contains a partially exhaustedreagent. This servesto remove a substantial portion of the impurities present, after which the partially refined material passes into the second tower, which contains a fresh, or more highly concentrated, reagent. This serves to remove the impurities present to the desired extent. The process is continued until the reagent in the first tower is almost, or completely, exhausted, after which it is discarded and the partially exhausted reagent from the second column substituted for it. Fresh reagent then is added to the second column.

In this manner the material to-be treated and the treating agent pass through the system countercurrent to each other, the first continuously and the second in a discontinuous manner.

This may be modified such as by the continuous addition of fresh reagent to the second tower, the

continuous transfer of partially exhausted reagent to the firsttower, and the continuous withdrawal of more completely exhausted, or exhausted, reagent from the first tower. A completely continuous countercurrent treating system thus is achieved.

Any desired modification of these methods may be employed, and any number of treating towers or units may be used. It will be observed that in each of the cases discussed, the incoming material to be refined is contacted with partially exhausted reagent (maximum concentration of impurities-minimum concentration of reagent),

while theoutgoing material to be refined is contacted with fresh or morehighly concentrated reagent (minimum concentration of impuritiesmaximum concentration of reagent). Thus the two objectives to be sought, namely, practically complete, or complete, utilization of the reagent and substantial, or practically complete, removal of impurities from the material to be refined, are achieved. 1

As the limiting factor affecting the utilization of the reagent is' the proportion of insoluble polymers and/or residues which can be contained therein without seriously impairing its flowing properties, or thepassage of the gaseous material to be treated therethrough, it frequently happens that the quantity of insoluble material present is insufilcient to interfere seriously with the operation of the process when the refining agent present has been almost completely exhausted. In this case, the operation of the unit may be continued by the addition thereto of an additional quantity of the refining agent, and this process may be continued until the concentration or insoluble niai'erial in the reagent renders it too viscous to be used furtherin the process in a satisfactory manner.

In this connection, it is well to point out that the insoluble products formed during the reaction have a tendency to stabilize the sodium suspension andact to reduce the rate of settling of the finely divided sodium in certain cases. As this l viscous or insoluble products, their removal from. the suspending medium, suitable at the end of a refining cycle and prior to'the return of the suspendingv agent to the system, maybe -indi-.

cated. On the other hand, certain of these Iclaim:

- 1. A process for refining unsaturated hydrocarbon material having from one to two double bonds permolecule, said unsaturated hydrocarbon material being contaminated with impurity including acetylenic and-aldehyde material, comprising I passing said unsaturated hydrocarbon material at a temperature below 100 C. through a dispersion 'of a finely divided material selected from the group consisting of metals of group IA and group HA of the periodic system and alloys thereof, said dispersion being at, least one foot in thickness in the direction'of flow of said unsaturated hydrocarbon material and containing less than 30% by weight of said finely divided material, maintaining the concentration of said unsaturated hydrocarbon material in the reaction zone below 80% by weight of the total material present, while soluble polymers are sufficiently stable to actas a I suspending medium for the refining agent.

An example of procedure which may be con- 1 venientiy followed in the practice of my invention is as follows:

Example 1 A light oil fraction containing approximately isobutylene, as well as approximately 1% acetylenic hydrocarbons, 0.05% aldehydes, and other impurities} was passed continuously in the gaseous stateinto a xylene suspension of finely divided sodium contained in asteel column 2" in diameter at a temperature of 50 0.

Under the operating conditions chosen, the refining agent comprised a. 10% suspension of, finely divided sodium in a suspending. medium containing approximately 90% xyleneand 10% isobutylene fraction. The height of refining agentemployed was approximately 6 feet.

The refining operation was continued for a period of hours, the isobutylene-fraction being charged at; the rate of approximately 1000 grams per hour. 1 I

The product obtained was water-white in color and contained only 0.002% acetylenes. -The aldehydes present had been removed completely. The product was in a high state of purity and could be used for the production of polybutene or synthetic rubber, suitably by copolymerization with relatively small proportions of one or more diolefines.

In the specification and in the claims, the following terms have the indicated meanings.

The term "a metal of group IA and group 11A maintaining the rate of flow per hour of said unsaturated hydrocarbon material through said dis-, persion at less than four times the weight of dispersion medium employed, and removing said unsaturated hydrocarbon material less contaminated with impurity including acetylenic and aldehy'dematerial from said reaction zone, sufficiently rapidly to prevent a large loss of said onsaturated hydrocarbon material due to the polymerization thereof.

2. A process for refining unsaturated hydrocarbon material having from one to two double bonds per molecule, said unsaturated hydrocarbon material being contaminated with impurity including acetylenic material, which comprises continuously passing said unsaturated hydrocar-' bon material at a temperature below 80? 0. through a dispersion of a finely divided material selected from the group consisting of metals of group IA and group 115 of the periodic system and alloys thereof. said dispersion containing less than 20% by weight thereof of said finely divided material and being atleast two feet in thickness in the direction of fiow of said unsaturated hydrocarbon material, maintaining the concentration of said unsaturated hydrocarbon material in the reaction zone less than 10% by weight of the total material present, while maintaining a rate of flow per hour, of said unsaturated hydrocarbon material through said dispersion of less than of the periodic system is intended to mean one of a gr'oup consisting of lithium, sodium, potassium, rubidium, caesium, barium, strontium. and calcium.

The term alkali metal is sodium, potassium, rubidium,- and caesium.

The term finely divided is intended to meanbe understood that these are given by way of illustration. Therefore, changes, omissionaadditions, substitutions, and/or modifications may be made within the scope of the claims without departing from the spiirtof the invention.

v employed as define itive of the group of metals consisting of lithium,

twice the weight of dispersion medium employed, and continuously removing said unsaturated .hydrocarbon material less contaminated with impurity including acetylenic material from said reaction zone sufflciently rapidly to prevent a large loss of said unsaturated hydrocarbon material due terial being contaminated with impurity including aldehyde material, whichcomprises continu-' ously passing said unsaturated hydrocarbon materialat a temperature below 80 C- through a dispersion of ,a finely divided material selected I from the group consisting of metals of group'IA and group 11A of the periodic system and alloys thereof, said dispersion containing less than 20%.

by weight thereof of said finely divided material and being at least two feetin thickness in the direction of flow of said unsaturated hydrocarbon material, maintaining the concentration of said unsaturated hydrocarbon material in ,the' reaction zone less than 70% by weight of the total material present,- while maintaining a rate of flow per hour of saidunsaturated hydrocarbon material througb said dispersion of less than twice the tained in a mixture includingacetylenic mate-' rial, which comprises continuouslypassing said mixture in vapor phase under temperature conditlons below 100 0. through a dispersion of a finely divided alkali metal, said dispersion containing less than 30% by weight thereof of said finely divided alkali metal and being at least one foot in thickness in the the direction of fiow of said mixture, maintaining the concentration of said olefine material in the reaction zone less than 80% by weight of the total material present, while maintaining the 'rate of flow per hour of said mixture through said dispersion at less than four times the weight of dispersion medium em-.

ployed, and continuously removing said olefine material less contaminated with impurityincluding acetylenic material from said reaction zone sufiiciently rapidly to prevent a large loss of said olefine material due to polymerization thereof. 5. A process for the recovery of aliphatic olefine material from a mixture containing the same and containing impurity including acetylenic material, which comprises continuously passing said mixture in vapor phaseunder temperature coriditions below 80 0. through a dispersion of finely divided sodium, said dispersion containing less than 20% by weight thereof of said finely divided.

sodium and being at least two feet in thickness in the direction of flow of said mixture, malntalning the concentration of aliphatic olefine material in the reaction zone less than 70% by weight of the total material present, while maintaining a rate of flow per hour of said mixture through said dispersion of less .than twice the weight of dispersion medium employed, and continuously removing said aliphatic olefine material in vapor phase less contaminated with impurity including acetylenic material from said reaction zone sufilciently rapidly to prevent a large loss of said aliphatic olefine material due to polymerization thereof.

6. A process for the purification of aliphatic olefine material contained in admixture with impurity including aldehyde material, which comprises continuously passing said admixture in vapor phase at a temperature below 80 0. through a reaction zone containing a dispersion of finely divided sodium, said dispersion containing less than 20% by weight thereof of said finely divided sodium and being at least two feet in thickness in the direction of flow of said admixture, maintaining the concentration of aliphatic olefine material in said reaction zone less than 70% by weight of the total material present, while terial in vapor phase less contaminated with impurity including aldehyde material from said reaction zone sufiiciently rapidly to prevent a large 12 loss of aliphatic olefine material due to polymeriza'tion thereof.

"1. A process for the purification of isobutylene cont ined in admixture with impurity including acetylenic material. which comprises continuously passing said admixture in vapor phase at a temperature. below 100 C. through a dispersion of finely divided sodium, said dispersion being at least one foot in thickness in the direction of flow of said admixture and containing less than 30% by weight thereof of said finely divided sodium, maintaining the concentration of saidisobutylene in thereaction zone less than 80% by weight of the total material present, while maintaining the rate of fiow per hour ofsaid admixture through said dispersion at less than four times the weight of dispersion medium employed, and continuously removingisobutylene in vapor phase less contaminated with said impurity including acetylenic material from said reaction zone sufiiciently rapidly toprevent a large loss of said isobutylene due to polymerization thereof.

8. A process for the recovery of isobutylene from a mixture containing the same and containing impurity including acetylenic material. which comprises continuously passing said mixture in vapor phase at a temperature below C.

through a reaction zone containing a dispersion of finely dividedsodium at least the majority of the particles of which have adiameter of not more than 0.05", said dispersion containing less than by weight thereof of said'finely divided soduim and being at least one foot in thickness in the direction of fiow of said mixture. maintainper hour of said mixture through said dispersion of less than four times the weight of dispersion medium employed. and continuously removing isobutylene in vapor phase and less contaminated with said impurity including acetylenic' material from said reaction zone sufilciently rapidly to prevent a large loss of said isobutylene due to polymerization thereof.

prises continuously passingsald fraction in vapor phase at a temperature below 80 C. upwardly through a reaction zone containing a dispersion of finely divided sodium at least the majority of I the particles of which have a diameter of not more than 0.03", said dispersion containing less than 20% by weight thereof of said finely divided sodium and being at least two feet in thickness in the direction of flow of said fraction, maintaining the concentration of said isobutylene in said reaction zone less than 70% by weight of the total material present while maintaining a rate of fiow per hour of said, fraction .throughsaid dispersion of less than twice the weight of dispersion medium' employed: and continuously removing said fraction in vapor phase from the top of said reaction zone less contaminated with impurity including acetylenic material suiliciently rapidly to prevent a large loss of said isobutylene due to polymerization thereof.

' FRANK J. SODAY. 

